The invention relates to the field of sports involving sliding, to be more precise an alpine ski. More particularly, it relates to a ski which comprises a binding-raising zone formed by an extra thickness of the structure itself of the ski. The invention makes it possible to optimize the mechanical properties of a ski having such a structure. The invention also relates to a method which makes it possible to manufacture such skis.
Generally, the upper face of the ski is provided, in the zone of the runner, with a safety binding consisting of a stop and a heelpiece. For various reasons, in particular for facilitating the tipping of the ski from one edge onto the other, it is desired to elevate the elements of the binding in relation to the sole of the ski. This elevation can be achieved in various ways, for example by using a raising platform screwed, or more generally joined, to the upper face of the ski. A great many types of platform have already been proposed, such as in particular that described in document U.S. Pat. No. 5,879,019.
It has also been proposed to elevate the binding not by using an additional element attached to the ski but, on the contrary, by designing the structure of the ski in such a manner that it has an extra thickness which itself forms the raising zone. Thus, in document FR 2 718 650, a ski has been described, the structure of which comprises, in the region of the runner zone, an additional element elevating the upper face of the ski in relation to the zones of the tip and of the heel. This elevated portion forms a raising zone, on which the stop and the heelpiece are mounted. Another example of a raising zone produced by virtue of a special design of the structure itself of the ski is described in document FR 2 686 520, which corresponds to document U.S. Pat. No. 5,346,244.
It is clear that this raising zone formed by the structure has a major influence on the mechanical properties of the ski, giving rise in particular to considerable stiffening of the zone of the runner. One object of the invention is to modulate this influence so as to obtain a ski which can be optimized in terms of its dynamic behavior.
In document U.S. Pat. No. 2,196,925, a particular ski has been described, which has an elevated runner zone which is machined. To be more precise, the upper face of the runner zone comprises several through-slots which open into cavities let in laterally. In this way, the wedge of snow present under the sole of the boot is removed via the slots, in particular when it melts. The production of such skis is relatively complex, of course, because it calls for very specific machining operations which make the structure of the ski fragile and are incompatible with modern manufacturing techniques and composite structures.
The invention therefore relates to a method of manufacturing an alpine ski which comprises at least one binding-raising zone formed by an extra thickness of the structure of the ski forming a projection in the region of the zone of the runner. The ski may comprise a single raising zone which receives the two elements of the binding. This raising zone can also be divided into two parts, a first part receiving the stop, the other part the heelpiece. In certain types of design, only the stop, or indeed the heelpiece, may be mounted on a raising zone. In this method, the various component elements of the ski are, in a conventional manner, positioned in a mold, between a mold bottom and a mold cover.
The method as claimed in the invention is characterized in that:
before molding, additional elements extending into the mold are arranged above the bottom of the mold, between the bottom and the cover, and above each lateral face of the ski;
after molding, said additional elements are, at least in part, removed so as to form grooves in the lateral faces of the ski.
In other words, the characteristic grooves are obtained by, after molding, extracting the additional elements which project beyond the sides of the ski. These additional elements, if appropriate in the form of a wedge, are easy to extract because they have been positioned in the mold with a large zone protruding laterally.
In practice, the additional elements can be removed either in totality or in part after molding. Thus, if these additional elements are made of a relatively flexible and deformable material, they can be extracted by pulling out. When the elements are more rigid, they can be removed by machining. The grooves are then formed inside these additional elements.
According to the invention, the ski obtained in accordance with such a method therefore has a groove let in over at least a portion of the length of each of its lateral faces. This groove is located between the upper face of the raising zone and the edge of the ski.
In the region of the raising zone, on its lateral flanks, the ski comprises let-in portions which can extend over all or part of the length of the raising zone. These grooves can be produced in the raising zone itself, that is to say above the level at which the ski would lie if it did not comprise the raising zone. These grooves can also be located below this level, above the edges. The presence of these grooves, which form cavities, and in particular their length and their depth, influences the overall rigidity of the structure, in particular in the region of the zone of the runner. The behavior can thus, for example, resemble more closely that of a conventional ski provided with a platform attached to its upper face, while retaining the advantages of a raising zone integrated into the structure of the ski, in particular lightening.
In practice, the additional elements used in the manufacturing method can advantageously be parallel to the sole of the ski, so as to provide grooves essentially parallel to the upper face of the raising zone.
In a particular embodiment, the additional elements used in the method can be positioned so as to come into contact with one another. They thus make it possible to produce a through-zone when they are subsequently removed. This contact zone between the additional elements can be arranged in any region of the raising zone, preferably in the central region thereof.
In other words, the grooves let in on each of the lateral faces can meet to define, over at least part of their length, at least one opening passing through transversely below the upper face of the raising zone. In other words, the groove produced on one side of the ski is let in sufficiently deeply to open into the groove produced on the other side, and thus to form a zone free of material over the entire width of the ski.
These through-openings can also be produced independently of the characteristic grooves.
In practice, the through-opening is advantageously located longitudinally, essentially in the central region of the raising zone. In other words, the hollowed-out zone produced in or under the raising zone is situated between the zones receiving the stop and the heelpiece of the binding.
In practice, the bottoms of the opposite grooves define between them an essentially vertical partition located below the upper face of the raising zone. In other words, the structure of the ski comprises a region of a width smaller than the width of the ski, on which region a part of the raising zone lies. This region therefore forms a partition on which the upper part of the raising zone lies and via which the bearing forces are transmitted. This partition contributes to the overall rigidity of the raising zone, the design of which is moreover lightened by the presence of the characteristic grooves.
In a preferred embodiment, the ski comprises a through-opening and two partitions as described above, these partitions being located one in front of and one behind the through-opening. The partitions can thus advantageously be situated longitudinally straight below one of the elements of the binding, so as to allow good transmission of the forces in the direction of the sole of the ski.
The shape of the various partitions formed between the grooves can be different. Thus, these partitions can have a thickness, measured transversely in relation to the ski, which either is essentially constant or varies. To be more precise, the cross section of the partition can either be constant or develop in the direction of the length of the ski. In the latter case, this thickness may decrease to reach a minimum in the region of the limits of the hollowed-out through-zone.
The width of the partitions measured transversely can also vary with the height of the partition. In other words, this partition can have flanks which are not strictly vertical but, on the contrary, inclined. Thus, in a particular embodiment, the partition can, over at least a fraction of its length, extend in its lower part to close to the lateral faces of the ski, so as to contribute to the transmission of the bearing forces in the direction of the edges. In other words, in their upper part, the partitions have a relatively reduced width. This partition widens out in the downward direction, so as to have an essentially trapezoidal cross section. This design makes it possible to lighten the raising zone without impairing the vertical transmission of the bearing forces.
In certain particular embodiments, the partition can include at least one element made of a material which is lighter than the rest of the ski, so as to reduce the influence of the raising zone on the weight and the overall rigidity of the ski.
In practice, the upper part of the raising zone can advantageously include at least one rigid insert which is capable of receiving the screws for mounting the binding. This insert, located below the upper face of the raising zone, is made from a material which can receive the screws for mounting the binding with minimum risk of thread-stripping.
In practice, the grooves produced on the lateral faces of the ski can allow the positioning of particular binding elements. These elements are advantageously adapted so as to interact with the characteristic grooves produced in the ski. These grooves can therefore serve for holding the stop and/or the heelpiece in position and for the longitudinal adjustment of the position of these elements. Thus, when these grooves are parallel to the upper face of the raising zone, they can receive ribs oriented toward the median longitudinal plane of the ski, which are formed under a sliding block supporting the stop or the heelpiece.
In a particular embodiment, at least one safety binding element is mounted by means of a clamp system including lateral jaws interacting with the complementary lateral grooves of the ski. These jaws are advantageously held in position transversely on the ski by locking means.